Need a little advice on where to start here. The story.

95-E320 w/168k-km (about 100k miles). When the cruise control is engaged will driving in the 120km/hr to 130km/hr range, it will what I call surge...ie accellerate to a 1/2 km/hr faster then let off to 1/2km/hr lower than the set speed then repeat, all in the order of 2 seconds. This will repeat adnausium. Setting it to below 120km/hr (even 119km/hr) it doesn't do it.

Where does the speed sensor get its signal? Does anyone have a schematic?

Thanks

Ron